The top of the heap for 2013 documentaries has remained remarkably strong. It's a testament to the popularity and quality of films like Blackfish, 20 Feet From Stardom, and The Act of Killing that they have had such a stranglehold on the rankings. These are films that have proved to be popular with audiences and critics in what is shaping up to be a pretty great year. New films like After Tiller, Inequality for All, and Generation Iron are making their presence felt, though, with solid debuts on the list.

We're ranking the year's top documentaries every week, based on a super-secret algorithm that reflects box-office success, critical praise, social media presence, and overall buzziness (that's what makes it super-secret!). How did things shake out this week?

2013 Documentary Power Rankings

1. Blackfish: The case against Sea World, and indeed against keeping killer whales in captivity at all, is made with an impressively voluminous array of former trainers, handlers, and employees. An "issue" doc that makes an impressive prosecutorial case. Previous Rank: 1

2. Sound City: The story of the famed music studio is the second rock-themed winner of the 2013 documentary slate. It remains the only 2013 movie in any genre with a 100% score on Rotten Tomatoes. Previous Rank: 4

3. 20 Feet From Stardom: This supreme crowd-pleaser about backup singers has climbed to the top box-office slot among docs for the year. Here's hoping it opens across the country, because there is absolutely no reason this couldn't be a hit in every market. Previous Rank: 2

4. The Act of Killing: Another triumph of taking the documentary genre to new and creative places. Previous Rank: 3

5. Stories We Tell: Sarah Polley's family doc remains one of the year's creative triumphs. Previous Rank: 5

6. Generation Iron: A spiritual descendant to Pumping Iron, this look at professional bodybuilders, and the road to the Mr. Olympia competition features appearances by famous muscle-heads Arnold Schwarzenegger, Mickey Rourke, and Michael Jai White. Previous Rank: n/a

7. Inequality For All: This look at former Labor Secretary Robert Reich takes a hard look at the American economic situation. Previous Rank: n/a

8. Muscle Shoals: In a year where Sound City is riding so high, it's no surprise that this movie, another look at a famous music studio, this time the titular Muscle Shoals in Alabama, is also hitting big with viewers. Previous Rank: n/a

9. After Tiller: After a great reception at Sundance, this story of the dwindling number of third-trimester abortion providers after the murder of Dr. George Tiller in 2009 has been a big success with critics. Previous Rank: n/a

10. Call Me Kuchu: This heartbreaking story of gays in Uganda has struggled to find placement in theaters, but those who do see it have raved about it. Previous Rank: 10